Mitsubishi Lancer - Mirage 96 - 05 with 4G15 1.5 SOHC 12v engine.

Dummies Guide to Vehicle Modifications!

The Mitsubishi Lancer – Mirage 1.5 model is the base range model and was more commonly known as the GLi model until the recent introduction by Mitsubishi of the GLi 1.8 model for greater power. The 1.5 engine is very much your economy engine with only 64kw – 67kw of power depending upon your location. It can be modified easily and with surprising results.

It is never going to be a V8 eater unless you go the turbo route, but the results of minor modifications can be very satisfying and for the majority of car owners, using these cars as mobile sound factories and body kits, this suits them perfectly. The naturally aspirated packages also work extremely well with many new options now available, whilst the low boost turbo systems of course always give there large cousins something to be concerned about.

The most common upgrade we now do for these models is the DOHC head conversion which is worth by itself, 8kw but requires no computer modifications at all, working on the factory SOHC 12v computer. Utilising this as a baseline, we are now seeing the humble 4G15 engine go from 65kw up to around 110kw in naturally aspirated form and around 150kw with some medium level turbo boosting.

Not all mods are for power though, there are many area’s of braking and suspension that any stock car can always be improved with. Along with other drive line upgrades, you can have a smooth reliable car, with improved handling, and provide that little bit of sporty power to keep most people satisfied.

This section is to be used as a guide in your modification – we will be breaking this into sections to provide a well balanced vehicle. Additionally the modification package will be setup so that as you increase the power of the vehicle, your alternative items like brakes etc are matched to your new power level. This guide has also been done in an order which provides successive gains from the modifications power wise. Jumping say to number 20 first, may result in a LOSS of power until you have done other items to match its effect.

RPW does not take any responsibility for people performing these modifications on there car without professional involvement. Check with your local government regulations before modifying your car as these items may not be legal in your country.

Group 1 Modifications

The group 1 modifications are designed for the every day driver, wanting improvements across the board without sacrificing road comfort, fuel economy or drive ability. These are also the baseline modifications for the more extensive Group 2 modifications.  Standard horsepower for the vehicle is 65kw on average at the flywheel.

1. Quick Shifters

The Mitsubishi gear shifter system is one of the better ones on the market. But that does not mean that people do not want to improve them. This is one of those modifications that can be done at any time.

The RPW Modified units suit most people who want something to reduce the long throw and give a more precise feel to where the gears are located. For those performing any level of competition work, or just want something a little more extreme, the Rally Spec Unit reduces overall movement by as much as 65% over stock.

2. Air Filters & Cold Air Induction Kits

The factory air box system on these vehicles, is quite restrictive. There are several ways to free them up – we recommend two main options

  1. Fitment of a K&N Factory Replacement Air Filter for those wanting the Stock look, with improved air flow and throttle response
  2. Fitment of a RPW Cold Air Induction Kit. A polished stainless steel system is available with that show car quality looks, and price.

The Cold air kit relocates to the front bumper, pulling cold air especially where utilised with a after market front bumper. Of course a K&N large pod filter is used, RPW recommends purchasing one of our K&N Pre Filter Charger Kits that provides additional filtration and resistance to water.

The plastic pipe kit we honestly believe, other than being the cheapest, is one of the best bang for dollar modifications you can do.

This should produce an approximate gain of around 1 – 2kw with improved throttle response and torque.

3. Fuel Pressure Upgrades

This is the one thing we believe that these vehicles should always have fitted regardless of how little, or much you modify the vehicle. Quite simply the factory vehicle has been tuned for maximum Economy. This has resulted in a fairly large flat spot off idle when accelerating hard from a standing start of from a cruise mode situation. The reason for this is Mitsubishi has tuned very lean on the accelerator pump settings, resulting in the lack lustre performance on throttle, but excellent fuel economy.

  1. Fitment of the Fuel Pressure Regulator kit eliminates this flat spot, whilst only marginally reducing your fuel economy. Without going into huge detail, trust us when we say, flat spots are eliminated, your car will actually accelerate properly without hesitating and your fear of being run over at stop signs will diminish rapidly. This is an easy bolt on kit and can usually be done in around 1 hour maximum.
  2. A CNC Manufactured bored out fuel rail, which increases the fuel capacity within the fuel rail. This enables upon acceleration, a greater volume of fuel to become available before leaning out. This also reduces the tendency to pulse the fuel and create disturbances in the fuel flow, providing a smoother transition to power. This is a recommended upgrade for those looking to go multiple throttle bodies / forced induction later.

This will not produce any HP Gain, but will provide an approx 10ft/pd torque improvement at low rpm off idle.

4. Exhaust System Upgrade

Okay you have done the easy mods, now time to do something about the exhaust. Contrary to what many people believe, without any form of induction work or fuel work, fiting anexhaust upgrades are only marginally beneficial. The stock system on these vehicles is usually an Asthmatic 1 5/8″ system. At this point you must reach your first major decision on where you wish to go with the vehicle – in summary we recommend the following options

  1. Naturally Aspirated – Stock Computer – You are only after mild improvements to make the car sportier, but don’t intend to do any real serious mods. This being the case stick with replacement of the stock exhaust with either a rear muffler upgrade only 2″ oval shaped muffler unit, or complete it with a 2″ press bent exhaust system with new muffler and resonator. Cat converter should remain stock. Any larger on the system would not provide without sufficient more expensive mods, any real gains.
  2. Naturally Aspirated – Piggy Back ECU – you are after mild to medium improvements to make the car sportier, with slightly more than average vehicle modifications. This being the case, a 2 1/4″ diameter replacement exhaust with a new resonator and muffler. No need to go mandrel bent unless you have money to throw away. This setup will handle the majority of modifications we have listed short of turbo systems
  3. Naturally Aspirated – Haltech EMS – okay you are an extreme modder. Twin throttle bodies, DOHC Head Conversion, camshafts the list goes on. In this case either a 2 1/4″ mandrel bent system or a 2 1/2″ press bent system. Only real difference is addition of a 2 1/4″ or 2 1/2″ cat converter depending upon how extreme you are going
  4. Turbo Charged – no more need be said. But don’t go throwing your money away on a 3″ mandrel bent system. A 2 1/2″ press bent system, cat converter with Lukey units are more than you will ever need. Keeps the car quiet, no droning and has a great sound. Mandrel bent on the 2 1/2″ system could be done but honestly, you don’t need it.

These can produce small gains with the basic systems of around 2 – 5kw at the wheels, with increased rev ability and torque.

5. Suspension Upgrade – Level 1

Suspension Package? Level 1? What is this. Basically at this point you are still have a mildly modified vehicle and want to just improve the looks slightly and handling. In this situation the following

  1. Replacement of stock springs with some lowering units – either Lovell 30mm or 50mm lowered units depending upon how low you want to go.
  2. Fitment of a White Line rear sway bar. Reduces body roll without reducing drive ability.
  3. Fitment of a White Line strut brace. Reduces the tendency of the vehicle to float on the road and makes it less sensitive to changes in road camber, resulting in less need to constantly adjust the steering wheel to keep the car driving straight.

This package will proved a well balanced vehicle, capable of handling corners at higher speeds, will feel safer at higher speeds especially above 100km/hr. The steering will feel more precise and you will have overall more confidence in pushing the vehicle harder.

Group 2 Modifications

Okay the basics are done and you have a plan. The following mods require you to decide, which of the following ways you are going which will be

  1. Staying with the 1.5 SOHC Cylinder head assembly for some further mild tweeks mostly in braking and suspension.
  2. Upgrading to the 1.5 DOHC Cylinder head conversion, with more medium to extreme tweaks
  3. Looking to turbo charge with either the SOHC or DOHC cylinder head assy

First decision – SOHC or DOHC cylinder head. We can only say one thing here – go the DOHC every time. If you don’t want to do this then skip the next option and move on.

1. DOHC Conversion Package

The DOHC head conversion is quite simply the best option if you seriously want any more power from the vehicle. A Naturally aspirated tweaked DOHC package will outperform any SOHC variation short of turbocharging. Its superior flow characteristics cannot be beaten. By itself with the stock 1.5 SOHC computer this is worth 8kw at the flywheel with an increased working RPM range. This is a one day conversion which can be performed for under $2000.00 AUD$ by simply swapping the cylinder head and other minor components.

We usually source a complete 2nd hand motor, replace the timing belt and water pump and then fit to the vehicle with RPW 4-1 Extractors, this engine comes standard with a 51mm throttle body.

You need to decide at this point because any extractor / turbocharger route requires a specific manifold / extractor for the specific cylinder head model which cannot be swapped across to the alternative.

This package upgrades the vehicle from 65kw on average to around 76kw on average at the flywheel. With above mods the vehicle should be close to around 80 – 83kw at the flywheel.

2. Extractor Upgrade

Not all extractors are equal. But in reality, any half decent designed unit will be an improvement over the stock manifold on the vehicle, although to date RPW is the only firm that manfactures a Extractor kit for the 1.5 DOHC cylinder heads.

RPW provides our own 4-1 race design kits which bolt up to the factory cat converters without any modifications required. Increased throttle response, torque and horsepower all result from this. If you have the DOHC cylinder head you will find the results are even more impressive due to the higher flow characteristics of the DOHC head.

If your plan is to go turbo, then save your money and jump ahead several more levels. This is not for you. For everyone else, this will complete the balance of your exhaust system modifications.

This package adds around 5kw at the flywheel with increased torque and improved upper acceleration and rpm range.

3. Single Throttle Body Upgrade / Thermo Block Kit

Time to look at improving throttle response again. Now if you are wanting to go a little more extreme, to a twin system then you need to wait a little longer. For everyone else, time to start looking at improving throttle response, even if you are going turbo.

The stock throttle body on the 4G15 SOHC engine is 46mm and the DOHC engine is a 51mm (Not convinced to go a DOHC yet?). For the majority of owners to do the following

  1. For all SOHC owners, upgrading the stock to our bored out 51mm or a 55mm is very beneficial. To be quite honest, on the SOHC models, anything with the stock manifold and cylinder head over 55mm is really just not effective. The cost V gain ratio is just not optimal for anything larger than a 55mm unit.
  2. For all DOHC owners, upgrading to our bored out 55mm is extremely beneficial.
  3. For DOHC owners with upcoming computer mods (Piggy back ECU) then a 60mm is also very beneficial if you are remaining Naturally Aspirated and don’t plan on going to a twin system. If you are going to a turbo, then stay with the 55mm.

Whilst this work is being done, we recommend fitting at the same time a RPW Thermo Block Kit. Consider this an extension of the cold air induction kit be reducing heat soak into the intake manifold from the engine and the throttle body which have hot water running through them. This drops the average intake temperatures by 25% overall resulting in improved combustion, fuel economy and throttle response.

This package adds 1 – 2 kw at the flywheel, but does improve throttle response and low rpm driveability. The thermo block kit reduces heat soak and this allows the engine to maintain maximum ignition timing with max throttle response.

4. Brake Upgrades – to suit all future modifications

Before doing any further power or suspension modifications, brakes now need to be seriously looked at. The stock brakes on the front of the lancer is a 235mm single piston calliper package with drum rear brakes. Atrocious and disastrous is one of many words used in relation to the Mitsubishi brake system on these vehicles. Below in increasing order is the packages we recommend. The stock brakes run a single piston 235mm rotor package.

  1. For those wanting something marginally better, and are not planning on doing ANY MORE Horsepower mods, then minor upgrading of front brakes only. Retaining stock callipers, fitting of some EBC Green Stuff brake pads and slotted Rotors is very beneficial. Improved braking by around 25% with better feel and dramatically less brake fade.
  2. Next package recommend is to replace the rear drum brakes with a RPW Rear Disc Conversion package. This fits a Mitsubishi 260mm rear disc package with EBC Black Stuff brake pads, slotted rotors, handbrake cables etc as a complete bolt on kit. This in combination with the above brake package, will suit all but the most hardcore modifiers. Great for looks as well. Braking is improved by around another 10% with much reduced brake fade again, especially as the speed of the vehicle reduces and the rear brakes become more effective.
  3. For those wanting the final level of brakes, fitting of a 276mm Twin Piston front brake package and brake master cylinder upgrade is the final step. This part is absolutely necessary for anyone wanting to turbo charge there vehicle in order to enable it to be permitted by the Australian Police to be licensed with a turbocharger conversion. Guaranteed no brake fade and this large rotor will fit very nicely inside of any 15″ or larger rim.

5. Suspension Modifications – Level 2

Okay ready to take the final plunge for power and hit that turbocharger or twin throttle body with computer. Wrong. Lets take a look at your suspension again. Factory shock absorbers will incresae your braking distance, especially if they have been running inside lowered springs for 10 – 20,000km. They are marginal at best when new. Time to go for more extreme options

Shock Absorber Options – three choices here with standard type strut assemblies

  1. Fitment of KYB Excel-G replacement units for the more budget conscious. Retains improved handling over stock.
  2. Fitment of KYB AGX units. These are externally adjustable and are perfect for the all round street / strip / circuit car. You can set them soft when your on the road, hard when your driving hard. Adjustment takes less than 1 minute
  3. Fitment if Koni Sports Inserts. These are similar to the KYB AGX units, but are serviceable and provide that little bit more control. They are a more precise unit, externally adjustable on the front only, internally adjustable on the rear. For the more sports conscious person these could be the better choice.

Coil over Strut Assemblies

  1. The Tien units specifically manufactured for Australian Conditions. To put it quite simply, many Japanese units are set very very hard, so even on there softest unit the car is very harsh, hurts kidney’s and actually has worse handling as it skips all over the road. The hardest setting on the Tien units, are equal to the softest setting on the Japanese normal imported units.
  2. These Tien Units are also available to be electronically adjusted on there rebound rates via up to one independent controller per corner, or one controller on all four units as an example. Mostly for extreme racing only.
  3. K-Sport

The final items to improve your suspension is as follows

  1. Fitment of a Upgraded front engine mount. This polyurethane improved unit, reduces axle tramp and engine movement. Increases traction and reduces the vehicle ability to get that dreaded engine bounce especially on wet roads. Any serious drag racer would feel the benefits of one of these straight away.
  2. Fitment of a Whiteline Anti Lift kit to the front lower control arms. In essence, this increases the caster of the front lower control arms and lowers there centre of balance, to provide a reduced tendency to “Lift” the front of the car upon accelerating. Requires a wheel alignment straight away.
  3. Fitment of a White Line rear strut brace (In Coupe Models Only) for additional reduced body movement.

RPW Does not recommend replacing the balance of the vehicle rubber mounts with Polyurethane ones for any street going vehicle unless being used for competition use. This results in a very very harsh vehicle on the road with much increased road noise and vibration. We feel the packages we have recommended provide that best balance of street vehicle and performance without sacrificing drive ability.

6. Drive Line Upgrades

There are three main drive line upgrades which can be done, which go a long way towards improving the reliability of the engine as well as drive ability.

  1. Clutch Kit – At some point your clutch will need upgrading. Two options available – for naturally aspirated drivers a standard cover plate with a semi ceramic five pucker clutch disc package. This will increase clutch efficiency by 50% without any extra pedal effort required. For turbocharged vehicles, this is upgraded to a Heavy Duty unit with the cover plate strengthened by an additional 25%. This provides slightly increased pedal effort and more tendency to be shuddery on take off’s but will handle the higher torque characteristics of a turbo.
  2. Lightweight Billet Flywheel – this has two benefits being increased strength over stock units and also make the semi ceramic clutch units more drivable by not allowing them to shudder as much. Second benefit is that they are lighter and enable the engine to reve easier, faster with less reciprocating weight. No loss of torque but more willingness to rev quicker and harder.

Group 3 Modifications

Now we are down to the serious modifiers. You are usually DOHC head converters, with plans on going turbo or serious Naturally Aspirated Twin Throttle body packages. Comfort and drive ability is usually second to engine performance and speed is your goal. These next levels are also the most expensive ones, but be warned, if you have not done any of the Group 1 or 2 Modifications yet, you are WASTING YOUR TIME AND MONEY. Finish them first.

1. Computer Modifications

Okay two choices. EMS, Re-flash Factory ECU or Piggy Back. Pro’s and Con’s. But We like to think of it this way.

  1. If you are still budget conscious (And your at Group 3?), then stick with the piggy back. Don’t run more than 12 psi boost or go more than say a twin 46mm throttle body package and definitely don’t do any camshaft work. You will be fine.
  2. Your not budget conscious within reason. Then EMS is the way to go. Much more advanced tuning, with options like shift lights, in built boost controllers, many many more mapping points, much finer tuning if your going over 12 psi boost or doing cam work etc this is the ONLY choice. Additionally the stock ECU even with a piggy back is unable to cope with any camshaft changes at all.

Some model ECU’s we can re-flash. We can handle virtually any combination of modifications except for turbo-charging. Great option, no cutting or wiring and perfect for those with low to medium level of modifications.

Haltech Interceptor / Greddy Emanage systems – provide a great unit for baseline tuning. The Haltech we recommend for people who have gone all the through the Group 1 & 2 level modifications, but don’t plan on going any further. The Greddy Emanage we recommend if you are going for a turbo / twin throttle body conversion due to its ability to be able to tune with larger injectors and tune properly (To a degree) with boost.

Haltech EMS systems are what RPW specialises in. We make our own plug and play ECU packages which means we can have your car running in around 15 minutes with a Haltech EMS system on there. There is the E6X for those wanting something simple, or the Haltech E8 for those wanting the best. With the inbuilt boost controllers, and hosts of other functions, these are way ahead of trying do piece together a piggy back with separate boost controllers, shift lights, gauges etc.

Note that we do not recommend plug in pre programmed computer chips. These are not tuned in real time on a dyno to suit your individual car. As you modify your vehicle you move further away from the standard average formulae of your engine output. This requires significant tuning and can only be done in real time, not on a computer 3000miles away from your car.

The interceptor units usually provide around a 5kw gain at the flywheel, with improved drive ability and torque. The full EMS units provide a little more at this point, but really show there benefit later with more extensive modifications.

2. Intake Manifold Upgrade / Twin Throttle Body Conversion

If you are remaining Naturally Aspirated you have several options.

  1. First you can go for a single throttle body RPW Performer Intake Manifold with Internal Ram Tubes. Massive throttle response, Haltech piggy back system great looks without extreme levels of tuning required. Significant torque improvements and can be utilised up to a single 60mm throttle body
  2. Upgrade utilising stock manifold, modified with fitment of a second throttle body – twin throttle body conversion. Either twin 46mm or twin 51mm throttle bodies work very nicely for a progressive throttle response and great top end rush of power. This system is fantastic and highly recommended if insurance premiums are a worry. Requires a Greddy Emanage to run this effectively.
  3. The third option is a combination of a RPW Performer Intake Manifold and twin throttle body. Massive plenum chamber, improved air flow, progressive throttle response, this is nearly equivalent to a quad throttle body kit without the side effects and all of the benefits. Massive air flow and the ability to tune with a piggy back or EMS system. Not turbo compatible of course.

The twin / single manifold upgrades in n/a form can take the car with tuning up as high as around 110 – 115 kw at the flywheel. Twin units produce much stronger mid range acceleration, single units much broader torque from a lower rpm range.

3. Turbocharger Conversion Package

What more can we say other than your a horsepower and boost Junkie. Welcome to the rest of the world. This combines extreme levels of torque and power, with neck snapping acceleration. It comes at a cost though, increased fuel economy, higher insurance and lots of money. But lets get something clear first.

  1. Anyone believing they can effectively fit a turbo kit on there car safely, properly and legally for under $5000.00 AUD$ is just plain dreaming.
  2. These engines in stock form will not handle above 1 PSI boost without aftermarket computer management despite what people believe. 25 : 1 rising rate fuel pressure regulators, larger injectors, moving the distributor to retard timing all these tricks – none work. Don’t skimp.
  3. 5th Injector systems are something that came and died in the 80’s. Quite simply this does not distribute fuel properly to all cylinders, and still does not provide ignition timing adjustment

Do the job properly and although it may cost more, it will last longer, provide trouble free maintenance and be everything you want it to be.

  1. For boost levels up to 10 psi can be done safety on the stock head gasket dependant upon tuning and inter-cooler efficiency.
  2. For boost levels up to 14 psi requires an upgraded decompression head gasket which RPW manufactures.
  3. Do not boost above 14 psi on the stock piston / conrod set-up otherwise you will learn what a banana conrod looks like.

The 4G15 SOHC engine at around 12 psi is good for around 130kw at the flywheel at the extreme. The DOHC engine for the same boost is good for around 150kw at the extreme. With forged components you can go up to as high as 180kw reasonably at around 20 psi boost

Our final advice – if 150kw is not enough for you – the finish reading this page, and instead either look for another car or look to do a engine swap to a larger Mitsubishi engine.

Did you like our guide? Something did not make sense. Please let us know and we will try to update this with more relevant information etc. We hope this helps you plan your vehicle modifications in a more informed manner.